IND issues Area Forecast Discussion (AFD) at Nov 16, 9:49 AM EST307
FXUS63 KIND 161449
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
949 AM EST Sat Nov 16 2024
.KEY MESSAGES...
- Warming trend back to the 60s begins Sunday
- Wind gusts in excess of 30 mph next Tuesday and Thursday
- Potential for first snow Wednesday night into Thursday
&&
.FORECAST UPDATE...
Issued at 949 AM EST Sat Nov 16 2024
Stratus remains stuck across much of the Great Lakes and eastern
Midwest this morning as low level moisture persists beneath a sharp
inversion. Temps have moved little over the last 24 to 36
hours...and are primarily in the mid and upper 40s this morning.
The stratus continues as the primary forecast challenge in the near
term...and there are several signs that the deck will be difficult
to erode over much of the forecast area throughout the rest of the
day.
The lack of substantial flow through the boundary layer is one
factor in why the stratus has remained so stubborn but as the
surface ridge shifts east by this afternoon...winds will veer to a
southeast direction although they will remain light. Subsidence will
deepen and advect north into the area today as well courtesy of the
return southeasterly flow. Ultimately...this will promote the
continued presence of the boundary layer inversion with the
subsidence and dry air increasing in the mid levels serving to
perhaps even strengthen the inversion into the afternoon.
Have trended more pessimistic with any clearing for the rest of the
day...with the potential for any cloud breaks and sunshine likely to
be confined to the lower Wabash Valley based on satellite trends
currently...and perhaps by late day over far southern portions of
the forecast area. This will have an impact on temp rises which we
had already tempered based on persistence and trends of the last
couple days. May see highs approach 60 in the lower Wabash Valley by
late afternoon but likely will only see low to perhaps mid 50s
elsewhere.
Zone and grid updates out.
&&
.SHORT TERM (Today and tonight)...
Issued at 300 AM EST Sat Nov 16 2024
Conditions have remained relatively stagnant the past 24 hours as
low stratus clouds have been stuck over the entire region. Latest
surface analysis shows an area of high pressure directly overhead
with reports of ceilings around 2000-2500ft agl. ACARs soundings
from around the region reveal the stratus is stuck under a strong
subsidence inversion trapping low level moisture near the surface.
The low sun angle this time of year struggles to heat the boundary
layer enough to break the inversion and lift the clouds out of the
area. Due to such a saturated environment with heavy cloud cover,
the past 24 hours have only seen a diurnal temperature range of
around 3 degrees in many spots, with temperatures stuck in the upper
40s. This same pattern continues through the rest of the morning
hours today.
Short term guidance does indicate the surface high and associated
ridging pushing north and east throughout the day, with winds
becoming southerly to southwesterly through the column. Increasing
winds and warm air advection may work to erode some of the low
clouds, especially across portions of Southern and Western Indiana.
Still thinking guidance may be pushing out cloud cover too quickly
further north and east, so have kept highs around the NBM25th
percentile for much of the region resulting in little diurnal
temperature ranges once again. Current forecast calls for highs in
the low to mid 50s areawide with the warmest locations in SW
Indiana. These numbers still may be too warm for Central and
Northeast Indiana if clouds do not break up by the evening.
&&
.LONG TERM (Sunday through Friday)...
Issued at 309 AM EST Sat Nov 16 2024
A significant change is on the horizon for the long term portion of
the forecast.
Well above normal temperatures will persist into the early portion
of the work week, with highs in the 60s Sunday into Tuesday as upper
level ridging and broad southerly/southwesterly flow through the
depth of the troposphere persists ahead of a large incoming low
pressure system.
Although some precipitation chances will be needed as early as
Sunday night, the highest likelihood of rainfall will come late
Monday into early Tuesday as the primary warm conveyor belt
associated with the potent, wrapped-up low pushes through the
region. That said, rainfall amounts may be limited by active
occlusion occurring with the low, which could act to split more
significant moisture between the deformation zone near and northwest
of the low, which will pass to our northwest, and the low level WCB,
which may be maximized more to our south and east.
In the wake of this first system, a second upper level low is likely
to drop into the Midwest and reinforce the first, potentially
leading to rapid cyclogenesis somewhere in the region Wednesday into
Thursday, though confidence is low on exact placement and timing of
this secondary cyclogenesis.
This secondary system will require reintroduction of precipitation
chances after a brief break Tuesday night, with high PoPs,
especially Wednesday night into Thursday as the surface low pivots
around the larger upper level low. Temperature profiles may be
borderline, but there is a non-zero chance for the first snowflakes
of the season to fly Wednesday night into early Thursday, perhaps
aided by much above normal lake temperatures which could add lake
enhancement to the equation. Again, between the timing and placement
of this second system, uncertainties with respect to the strength of
the cold intrusion into the area, and this being a significantly
unusual evolution of a synoptic system in this region, confidence is
low at this time in details, but suffice to say, the latter part of
this week will turn sharply cooler, windier, and wetter than the
early portion of the week, and than much of the young cool season
has been thus far.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 638 AM EST Sat Nov 16 2024
Impacts:
- MVFR cigs slowly lifting this afternoon
Discussion:
Latest satellite imagery shows a large area of stratus across the
Great Lakes and Ohio Valley as moisture remains trapped in the
boundary layer under a strong subsidence inversion aloft.
Observations still indicate cigs around 2000-2500ft agl across the
region this morning. Cigs should remain at MVFR levels through the
rest of the morning hours. Patchy fog possible at KLAF, KHUF, and
KBMG through around sunrise; however with thick stratus around, not
expecting widespread fog and visibility reductions. As high pressure
shifts eastward today, expect cigs to lift and break up by the
evening hours. It is worth mentioning that confidence is lower on
the timing of the raising ceilings and clouds breaking.
Calm to very light easterly winds early this morning will become
southeast 6-11 kts by this afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...Ryan
SHORT TERM...CM
LONG TERM...Nield
AVIATION...CM
Source:
IND issues Area Forecast Discussion (AFD) at Nov 16, 9:49 AM EST---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
